Performance of an order statistic based diversity combining M -ary frequency-hopping system in a partial-band jamming environment

An order-statistic-based combining technique is evaluated for fast frequency hopping spread spectrum receivers operating in the presence of partial-band noise (PBN) jamming. The method replaces the linear combining receiver with an outlier-resistance estimator based on order statistics. A practical algorithm that sums all but the largest of the received hops is advocated, and a diversity combining gain is realized. It is applicable to M-ary noncoherent frequency-shift-keying modulation at the expense of rejecting the largest of the received hops in each of the M channels. The worst-case PBN jammer is forced to cover a larger fraction of the hopping bandwidth. Two different receiver designs are examined: one has separate pseudorandom noise (PN) codes for each of the M channels, whereas the other employs a single PN code leading to a contiguous jamming environment. The independent jamming receiver was shown to have a degraded performance compared with the contiguous jamming receiver when linear combining is employed; however, with the advocated MVRC (maximum variate rejection combining) receiver the performance of both receiver designs in a PBN jamming environment is approximately equal